So, I know over half of this blog's followers are not moms, but I've got another mom-directed post to get off my chest. I searched the web high and low for this information when I was trying to prepare for our trips, and couldn't find it anywhere, so I'm hoping this helps out a few random Googlers in the same boat I was in.
R and I had two trips this spring that we were taking without the baby. But, since I was all gung-ho to keep nursing her, I basically went to some crazy measures to make sure she had breastmilk while we were away from each other. The easy part was pumping and freezing about 200 ounces of extra milk: I used the Lansinoh storage bags and froze the milk in 4 ounce increments. (As an aside, I liked the bags - of the couple hundred I've gone through, only a handful have broken.) The tough part was getting this frozen milk, which needs to be used within 24 hours of thawing and cannot be refrozen if thawed, from our place in the midwest to my parents' house in Dallas, where Julia was staying for this trip. The other tough part was transporting the milk that I pumped while away back to our house to restock that freezer stash. If you think I'm going to spend hours pumping in a hotel room while I'm on vacation just to dump that hard-earned baby food down the drain, you crazy.
The key for both those objectives was dry ice. We debated overnighting the milk to Dallas, but in the end opted to carry it down with me during my flight. I bought an insulated box from Control Temp Packaging and R.N.C. Industries via their Amazon store, and planned to check it just like another piece of luggage (thank goodness for Southwest and their baggage policy!). Even checking the milk as a third bag on Southwest was way cheaper than overnighting it using FedEx or UPS ($50 vs $100+), and checking it involved much less travel time from freezer to freezer. It was a little risky because the airlines can always lose a bag, but we had a direct flight and I felt comfortable enough.
Anyways, our flight was at 1:00, so I bought the dry ice the day before. I ended up at some warehouse that did mostly ice carvings and shaved ice machine rentals, but it worked out just fine. You can only carry on 5 lbs of dry ice in a package (which is the same limit imposed by FedEx and UPS by the way), but I bought 15 lbs because it was so cheap ($0.80/lb). That 15 lb block was about 10 lbs by the next morning after sitting overnight in my insulated box. Don't put dry ice in your freezer - they say it won't last any longer than if you store it in a cooler, and it'll mess with the temperature settings of your machine and make you sorry. A few hours before the flight, I broke that 10 lb block into pieces by dropping it on our garage floor, and got a few chunks that made up approximately 5 lbs. Wrapped those up in newspaper and put them on top of the frozen milk inside that insulated box. Packed it carefully, used newspaper to fill the holes, taped it up and away we went. (Don't make the seals airtight because you need somewhere for that CO2 to go when the ice sublimates, but you also don't need to like, poke holes in it to vent. A regular cardboard box should vent fine as long as you don't tape every single edge.) When I checked the bag with the airline, I just told the guy there was dry ice in it, yes the ice was less than five pounds, and all it required was an additional sticker. He did ask what the contents of the box were, and got totally flustered when I told him "breastmilk." He wrote "nursing milk" on the label instead, which made me giggle.
TSA did not open the box, which might have just been lucky on my part. But everything arrived frozen solid when we got to Dallas! There was still a decent-sized chunk of ice in the box when we got there. So, all in all, my 15 lb block turned into a 10 lb block after about 12 or 13 hours, and my 5 lb block was plenty sufficient to keep the milk frozen for about seven hours of travel time. Success!
To get milk back home safely, I've used gel packs to keep milk chilled in my checked luggage. I've also used gel packs to keep milk frozen in checked luggage, but they definitely only barely kept things frozen during travel time. The thinner parts of the frozen bags were thawed, so I wouldn't recommend that or do that again. You hate to throw out a 4 oz bag because one little end of it started to thaw.
What we did this trip, since it was five days long and the milk needs to be frozen within a few days of pumping, was overnight the first few days' worth of milk - chilled but not frozen - back to Midwest, where some relatives were kind enough to receive the package and put the milk into the freezer for us. I bought a cheap, hard-sided cooler at WalMart, and two 3 lb bricks of dry ice from a local grocery store (call around but I guess it's not that uncommon for a grocery store to sell dry ice - who knew?). I put the dry ice in the cooler, put the chilled milk on top, boxed it up, and the hotel overnighted it out for me. Turned out the dry ice froze most - but not all - of the milk in transit, but since there was still dry ice in the cooler when the package arrived at its destination, I'm assuming the temperature never fluctuated back up and the non-frozen milk didn't go through a freeze/thaw cycle in transit. If I were to do this again, I'd distribute the milk more evenly around the dry ice so that everything would freeze and stay frozen, instead of the bags furthest away from the ice remaining liquid, which is what happened this time. My fault though, since I put the ice on the bottom of the cooler rather than the milk (the cold air from the ice sinks - duh Jess).
Anyways, the milk I pumped for the second half of the trip got chilled, then put into two soft-sided coolers (one inside the other) with a big frozen gel pack wrapped up in a washcloth. Then it got carried on - I declared it ahead of time at security and TSA was totally cool with it; honestly they didn't even look inside the cooler to check it out. I brought extra baggies in case I needed to dump the gel pack - thinking I could fill them up with ice on the other side of security - but (go figure) a frozen gel pack is fine to get through security as long as it's completely frozen solid. This kept the milk chilled for my travel time (another seven hours or so). I've also checked chilled milk before using the same set-up, and it also went fine; I just prefer to carry it on in case the airline loses my bag.
I asked our hotels to provide mini-fridges in our rooms, which wasn't a problem at all. The mini-fridges all had little bitty freezer compartments to freeze the gel packs. The shipping department at the Ritz was also very accommodating in helping me overnight my package. (By contrast, the Bellagio, while ultimately coming through for me, was all, "Well maybe we'll have a fridge for your room when you get here, maybe not. Can't guarantee it. Just have to see when you get here.") The key things to remember are storage bags and cleaning materials for the pump parts and bottles (if you pump into bottles like I do instead of directly into bags). I brought my electric pump for use in the hotel room, and a manual pump for pumping on the plane, which was WAY more discreet and convenient. (Remember to pack a nursing cover so you're not trying to hide awkwardly behind your husband's jacket.) Also remember to pack some extra ziploc baggies for ice in case you end up having to toss a gel pack (I used these on the flight out when I didn't pack a gel pack in my carry-on but pumped on the plane). Most airports have a family restroom or an itty bitty space in the women's restroom where you can pump discreetly.
It's tough, and honestly looking back, I kind of wish I had just decided to supplement with formula instead of go through all this trouble, but it's doable. Dry ice and preparation... and you too can go through an inordinate amount of hassle to keep your baby exclusively on breastmilk while traveling without her!